"I'm not sure it's a good idea that one person plays all these roles," said Toni-Michelle C. Travis, a political analyst and professor of government at George Mason University told the Times. "The entanglements become greater and greater, and that can lead to conflict-of-interest questions at some point.

"People are slipping across the lines to play multiple roles."

The firms of McCain senior adviser Charlie Black and campaign co-chairman Thomas Loeffler have earned millions from foreign governments, lobbying the White House, Congress and others, the Times said.

Loeffler, a former Texas congressman whose firm has received millions of dollars from Saudi Arabia, said he had never spoken about his clients with McCain, the senator from Arizona, who he said often voted against his clients' interests.

Black expressed that he possesses a similar ability to keep his interests separated.

"If an issue comes up, I don't participate in the discussion," he said.